An electrophoretic display device belongs to a reflective-type display device, with good sunlight readability, and also with advantages of plain paper and an electronic display. Because the electrophoretic display technology has advantages such as bistability, low power consumption, low costs and tremendous potential for achieving flexible display, it is the best technology for realizing industrialization of electronic paper (e-paper).
At present, implementations of the electrophoretic display technology may have the following ways. Titanium dioxide particles of approximate 1 mm in diameter are dispersed in hydrocarbon oil, and black dye is also added to the hydrocarbon oil, along with surfactants and charge-control agents that cause the white titanium dioxide particles to carry electric charges; this mixture is placed between two parallel, conductive plates that are separated by a gap of 10-100 mm, and when a voltage is applied across the two conductive plates, the charged titanium dioxide particles will migrate electrophoretically to the conductive plate bearing the opposite electric charges. When the titanium dioxide particles are located at the front side (display surface) of the display, the display screen appears white, this is because light is reflected back to a viewer by the titanium dioxide particles; when the particles are located at the rear side of the display, the display appears black, this is because the incident light is absorbed by the black dye. If the electrode on the rear side of the display is divided into a plurality of micro image elements (pixels), then an image can be formed by applying an appropriate voltage to each region of the display to create a pattern of reflecting and absorbing regions.
Gyricon (rotating balls) is another excellent electrophoretic display method, but it possesses shortcomings of small rotation angles and slow rotation speeds, etc., and therefore it is difficult to achieve a rich-color image display and fast image switching.